Line voltage regulator



April 6, 1954 E. A. LINK 2,674,716

- LINE VOLTAGE REGULATOR Filed March 29, 1951 Q mmmn %v INVENTOR.

Patented Apr. 6, 1954 LINE VOLTAGE REGULATOR Edwin A. Link, Milwaukee, Wis., assignor to R T & E Company, a corporation of Illinois Application March 29, 1951, Serial No. 218,233

9 Claims.

This invention relates to regulators and more particularly to step type line voltage regulators operative to effect the automatic maintenance of line voltage fluctuations within certain predetermined and permissible limits.

The need for equipment of this type, particularly on long rural distribution lines, has existed for many years. Presently overloaded circuits supplying power at inadequate voltage levels have resulted from too conservative estimates, at the time of line installations, of future load growth and present-day load requirements. This common condition of overloaded circuits has emphasized the need for line voltage regulating equipment which would function automatically to raise the line voltage before any point along the line drops below a minimum voltage limit and lower the voltage before any point on the line rises above a maximum voltage limit.

Distribution line voltage limits, when referred to a 120 volt base, are generally regulated to hold the output voltage at full load between 124 and 127' volts and at light load between 120 and 124 volts; while the distribution line voltage limits, at the consumers distribution transformers, have arbitrarily been established between 116 and 127 volts. From these figures, it will be apparent that there is a permissible line voltage fluctuation within the established predetermined limits.

The present invention provides a step type line voltage regulator which functions automaticalh to maintain the desired distribution line voltage Within the predetermined limits by the operation of a control device which initiates a boost operation of the regulator when the voltage on the load side of the regulator drops to 120 volts or lower and which cuts out the boost operation of the regulator when the voltage on the load side of the regulator rises to 127 volts or higher.

The primary objects of the present invention resides in the provision of a new and improved step type line voltage regulator which operates automatically to maintain the load line voltage within predetermined and permissible limits.

Another object of the present invention resides in the provision of a new and improved step type line voltage regulator having a unitary core and coil structure with the coil including shunt and series windings arranged in fixed autotransformer relationship.

Another object of the present invention resides in the provision of a new and improved step type line voltage regulator having a unitary core and coil structure with the coil including shunt, series and control windings arranged in fixed autotransiormer relationship; with the control winding having a definite ratio with the load side voltage of the regulator.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator having a control means responsive to the fluctuations in the load line voltage, beyond the predetermined and permissible limits, to efiect the operation of the regulator to maintain the load line voltage within the predetermined limits.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator having control means responsive to the fluctuations in the load line voltage, a switch and switch operating means; with the switch operating means responding to operation of the control means to alter the switch position in accordance with the demands of the control means.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator having a time delay means associated with a switch operating means; the time delay means serving to insure the change of the switch position only upon the persistence of the voltage change demand of the control device for a period of time not less than the time delay period of the time delay means.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator having a switch operating means with rest and active positions and driving means responsive to control means for returning the switch operating means to its rest position upon the termination of any voltage change demand impressed upon the regulator by the control device.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator including a control circuit provided with a limit switch which functions to terminate the active movement of the switch operating means to alter the position of the switch.

Another object of the invention resides in the provision of a new and improved step type line voltage regulator including a control circuit having a neutralizing switch which functions to terminate the return movement of the switch operating means when it reaches its rest position after the completion of a change of position of the switch in response to a voltage change demand impressed upon the regulator by the control means.

Other objects and advantages of the present invention will become apparent from the following description of the illustrative embodiment shown in the accompanying drawing.

The sole figure of the drawing is a schematic diagram of a line voltage regulator, constructed in accordance with the teachings of the present invention, showing in the illustrative embodiment of the invention a preferred combination of both mechanical and electrical means together with operating and control circuits.

The device chosen for illustrative purposes in the accompanying drawing comprises a single step line type voltage regulator. The operating elements of the regulator are contained in a sealed steel tank provided with pole mounting hangers so that the regulator may be mounted in a conventional manner on a line service pole. The control mechanism for the regulator is preferably contained in a control box, adapted for ready inspection, mounted either on the exterior wall of the enclosure tank or remote therefrom in case it is deemed more expedient to mount it near the base of'the pole supporting the regulator; where it is readily accessible for inspection, adjustment. or replacement without necessitating the climbing of the pole to gain access to the control box.

Referring to the schematic diagram, the illustratedstep type line voltage regulator comprises generally a unitary core and coil structure IE), a switch II, operative to selectively establish one of a plurality of connections between the power input line and the load line, a switch operating member I2, a driving means I3 for the switch operating member, a time delay mechanism I4 interposed between the driving means Bend the switch operating member I2, and a control device I5 responsive to voltage fluctuationson the load'line, beyond the predetermined andpermissible limits, to initiate the operation of the driving means I3 to effect the shifting of the position of. the switch If in accordance with the demands of the control device I5.

A detailed description of the main and control circuits of the device will, be deferred until such time as the structure and functions of the severaloperatingparts of the regulator have been discussed.

The unitary core and coil structure It is contained within a sealed steel tank and comprises a core I6 anda coil IT, preferably of the shell type. The coil I1 includes a plurality of Windings comprising a shunt winding I8, a series winding l9 and a control winding 2!! all of which are in fixed autotransformer relationship and so arranged that the ratio of transformation of the load side voltage of the regulator to the control winding voltage remains constant; A shield, 2| preferably formed of copper and grounded with-the coils I8, I!) and 2|],through connection to the tank wall, isdisposed between the shunt and control windings I8 and 20; respectively, to prevent surge voltages from being induced capacitlvely'into the control circuit. The shield 2| serves a further purpose in that it provides safety protection to the lineman by preventing high voltages from occurring in the control circuit, should the unit become faulty.

The switch II and its associated mechanisms, the switch operating member I2, the driving means I3and the timeudelay mechanism comprise a. unitary assembly unit arranged for mounting within the sealedsteel tank and easily removable therefrom for the purposeof inspection, service or replacement. The switch II comprises an arm 22 mounted adjacent one end on a shaft 23 journalled for rocking movement in a suitable bearing member 24. A pair of oppositely projecting electrically connected contact elements 25 and 26 are mounted adjacent the free end of the movable switch arm 22. These contacts 251and126, serve respectively, to connect line contacts 21 and 28 with coil contacts 29 and 3!] dependent upon the position of the switch arm 22. A pin 3| positioned intermediate the ends of the arm 22 projects therefrom to provide an anchoring means for one end of a tension spring 32 which serves as a connector and actuating meansbetween the switch arm 22 and the switch operating member I2.

Theswitchoperating member I2 comprises an arm 33 having one end fixed to a shaft 34 through which motion is imparted to it. The shaft 34 is journalled for rotation in a pair of members 35 and 36. A pin 3T positioned adjacent the free end ofthe arm 33projects therefrom topro videan anchoringmeans'for the other end of It should be noted that the arrangement and positioning of the switch thetension spring 32'.

arm 22 andthe operating arm 33 together with their fulcrurnshafts 23 and-34'is such that movement of the switch operating arm 33 from its normal rest-position, to effect the-changeof-position of the switch arm 2'2from one set of'contacts to the other, results in the over center movement of the tension spring 32 to causethe switch arm 22 to snap quickly from oneset of contacts to the other. Suitable stops in the form of abutment members 38 are positioned in the path of travel of the arm 22to arrest its motion with the contacts 25 and 26' bridging the gap between the stationary line andcoil tap contacts.

The driving means I3, chosen for illustrative purposesin the drawing, comprises a reversible shaded polemotor- 39- having a magnetic field winding 40, and a pair of pole shading windings M and 42; and an armature -43'mounted on an armature shaft 44- which carries a driving gear 45 for transmitting motion tothe switch operating arm 33 through the medium of the timede lay mechanism I4.

The time delay mechanism I4, as illustrated in the drawing comprises a double reduction gear train including a couplet having a larger gear 46 meshing with-and driven by the gear Ali-on the armature shaft Manda smaller gear 41meslring with and driving a gear 48 flxedly mounted on the shaft 34' on which the arm'33' on the switch operating member: I2 is secured. The shaft 34 which carries the switch operating arm 33 as a unit remote from the tank, for example near the base of the pole on which; the regulator is mounted, to render itmore accessible for inspection; adjustment or replacement. In either instance, the electrical connectionstoand from the, control device may be .made: by; using suitable plug-in connections. The; control device- I5, as illustratedin the drawing, comprises a contact.makingvoltmeten-SI, includinga pri.

mary winding 52 and a secondary winding 53 connected to a heater 54 mounted on a shaft 55 to which is secured a pointer needle 56 having one end thereof readable against a ca1ibrated voltage scale 5'5 on the instrument and provided adjacent its other end with a contact element 58 movable with the needle 56, under the influence of voltage changes on the line side of the regulator, and adapted to establish selective electrical contact with adjustable low and high limit contacts 59 and Gil, respectively, built into the contact making voltmeter 5!. The adjustability of the limit contacts 59 and ti! serves to provide a simple and efiective way of making individual adjustments of the contacts to set the low and high limits and the permissible voltage fluctuation range beyond which the contact mal ing voltmeter 5! functions to effect automatic voltage compensation by energizing the control circuit and setting the driving means l3 in motion to effect the change of position of the switch H in accordance with the demands made on the voltmeter 5| by reason of a fluctuation of voltage on the load side of the regulator which has exceeded the permissible range of voltage variation.

The main circuit of the regulator includes a power line 6| connected with the power line contacts 21 and 28 of the switch H which contacts are selectively connected with the coil contacts 29 and through the bridging contacts 25 and 26 carried by the switch arm 22. The coil tap contact 29 is connected by a lead wire 62 to a tap on the coil I! at the juncture of the shunt and series windings i8 and 19, respectively. The other end of the series winding is is connected to a load line 63; while the other end of the shunt winding is is grounded. One end of the control winding 29 is grounded while its other end is connected by a lead 64 to a fuse 65 and a branch lead 66 to one end of the magnetic field winding of the shaded pole motor 39 while the other end of the winding 40 is grounded. With the switch I l in the position shown in the schematic drawing, which is the boost position, the series or booster winding I9 of the coil I! is thrown into the circuit between the power line SI and the load line 63 to effect the desired boost in load line voltage. When the switch H is snapped to its other position, the current from the power is a neutral one in which the series Or booster winding I9 of the coil I1 is not connected in the circuit between the power line 6! and the load line 63. It should be noted, at this time, that a resistor device 63 is connected across the incoming power line 6! and the load line (it. This resistor device has a voltage sensitive characteristic which provides surge protection to the series winding I9 of the coil I! and also serves to maintain continuity of current flow between the power line 6! and the load line 53 during the substantially instantaneous period of break in the switch circuit while the switch arm 22 is traveling from one positon in another.

The control circuit for the regulator is fed from current induced in the control winding ill of the coil I! through a branch lead 69 connected to the lead 65 where the fuse 65 provides protection for the control device I5 and the associated control circuit. The branch lead 69' carries current to the primary winding 52 of 6 the voltmeter 5!. The circuit through the primary winding 52 is completed by grounding the other end of the winding. The control current from the primary winding 52 is induced into the secondary winding 53 which tends to rotate the shaft 55 through the action of the heater 54 to cause the needle 5G to be deflected thus moving the the contact 58 toward either the low limit contact 59 or the high limit contact 60, in accordance with the trend of the fluctuation of voltage on the load side of the regulator. The high limit contact Bil of the voltmeter 5! is connected through a lead 10 to one contact of a two pole three position selector switch H, shown in automatic control position in the diagram; the other two positions of the selector switch are a fixed boost position or a fixed neutral position. With the selector switch H in the automatic control position, the lead 10 is connected to a lead '12, through one of the switch poles, which in turn is connected to the shading pole winding 4! the current for which is induced from the alternating field of the motor 39; and also to a contact 73 of a neutralizing switch M, and to a fixed contact 75 of a normally open limit switch it, the blade of which is grounded. The low limit contact 59 of the voltmeter 5! is connected through a lead H to a contact of the selector switch H disposed o-pposite to the contact with which the lead i0 is connected. The lead 11 is connected to a lead iii, through the other of the switch poles, which lead is in turn connected to the shading pole winding 42 or" the motor 39, and to a fixed contact E9 of the neutralizing switch 14 and also to a fixed contact 8!) of a normally open limit switch ti, the blade of which is grounded. Both low and high limit contact circuits are completed selectively through the movement of the neutralizing switch operating cam M which is fixedly mounted on the drive shaft M which effects movement of the driving arm 33 of the switch operating member it. When the cam 56 moves in a counter-clockwise direction it urges the spring biased blade of the neutralizing switch M upwardly to move a contact s2 carried by the blade into contact with the fixed contact iii on the lead is to close the circuit in the shading pole winding 42 and introduce into the circuit a resistance 33 the ends of which are connected respectively with the switch blade of the neutralizing switch M and the ground. When the cam 59 moves in a clockwise direction it permits the spring biased blade of the neutralizing switch M to move downwardly to close an electrical connection between the contact $22 the fixed contact 73 on the lead ii to introduce the resistance 33 into the circuit of the shading pole winding ii. The amount of rotation of the operating arm 22 of the switch is limited in both directions of travel by the action of the limit switch operating arm 49 which is also secured to the driving shaft 34. Movement of the switch operating arm 22 in a counter cloclb wise direction is terminated when the arm 49 closes the normally open limit switch 16 and in like manner, clockwise movement of the operating arm 22 is terminated when the arm 49 effects the closing of the normally open limit switch 8!. The control circuit is completed by the inclusion of an arc suppressor t t between the leads 12 and it for the purpose of insuring long life for the contacts of the volt* meter 5 I.

With the foregoing description of the several operating parts-of: the line voltage regulator" completed and the main; andcontrol circuits set up, a discussion of: the automatic operation of the devicewill serveto illustrate its effectiveness inimaintaining voltage on the load line side of the:

regulator within the predetermined and permissible limitsdesignated by the adjustably fixed .posi-. tioningof the low and high contacts 59 and 80,- re? spectively, of the contactmaking voltmeter 5|.

With'the regulator connected between the power lineGl and thezloadtline and the several elee ments of the regulator: positioned and connected in r the manner" shown in the schematic diagram,

thev regulatorois ready to function to maintain the voltage-onthe loadrside'of the regulator within the, desired predetermined limits as" set by the:

adjustment of: the high, and low limit contacts GOPandzSQ, respectively, of thecontact'making voltmeter 5|; Asthevoltageon the-load side of" the regulator: varies up and down, a corre-- sponding change is induoedinthe controliwinding20- of: thecoil- I! which impresses this vproportionate voltage-on: the contact making volt-' meter 5|i through the protective fuse 65 and. the :lead 69; causing upward'or-downward deflec-- tion of the needle 56 which carries theconta'ct 53. of the voltmeter 51; the control winding 20 of thecoi-li l1= also en? ergizes the magnetic field winding 40; of the. motor 39"through the fuse 65-and the lead-66: As

long as the voltageon the load side of the regulatoris maintainedwithin the limits-set by the position of the contacts fifl and B of the volt-i meter- 51, theymotor '39'will remain at rest with the switch operatingarm' 33-and:its associated control elements, the 'limitxswitch operating armi 43and the neutralizing switch'operatingv cam 50. being retained inactive positions. should the voltage in the circuit on the-load side: of

the a regulator-"rise above the hightlimit voltage set' by the adjustment of the contact 60 and persist above the high limit for a period of time greater than the time delay factor:built into the contact: making voltmeter which time delay is of 3 approximately one minute induration and serves-.toslowdown. the movementof the indi cating and' operating arm or needle 56 ofithe" voltmeter 5|; to "eliminate many undesirable contact operations which occur in other types of meters not soequipped, the'contact 5B of: the voltmeter will establishhcontact with the high limit contact 60to complete-the circuit through the shading polewinding 4land initiate the oounter clockwise rotation of the armature 43 of the motor 39. The counter-clockwise rotation of the motor transmits a counter-clockwise move ment to the-switch operating arm 33'through the medium of thetime delay mechanism- I4 in the form of a speed-reducing gear traincomprising gears 45; 4B, 41 and 48 interposed between" the armature shaft and the shaft 34 on which the switch operating arm-33 "and the limit switch operating arm 49' and the neutralizing switch operating cam'SO-are mounted. Thegear-reduction of the-time delay'mechanism is so :constructed that a period of approximately two minutes of continued rotation of the armature 43 is required to cause the switch operating'arrn' 38- to traversethe required distance, in=a counterclockwise direction, to' efiect the actuation of the switch ll bythrowingthestension spring;

which. connects the switch operating arm 33 and 'thetarm' 22501 the:- switch l .I; over center be tween the arms 22 and 33 and causing therbridgs ing/ contacts 25 and: 12.3: to; break: connection: be-

The .current induced in:

tween the power line and load linetcontacts- 2-1 and 29 and-snapinto its other position to establish contact betweenthe power line andload line contacts 28 and 33 to therebyeffect the removalor cutting out of the" series or booster. winding IQ of the coil I! from series connection between the power line GI and the load: line 63 and placing it in shunt connectionwith, the load line 53. The disconnecting of the-series winding I! from: its boostarrangement in the;

circuit results in the desired drop in the voltages onthe load side of the regulator, as long as the voltage onv the load side of. the regulator:

remains within the set range of permitted voltage fluctuation limits, no further operation of; the regulator will take place untila new cycle ofv operation is dictated bythe contact making voltmeter 5| underthe'influenceof excesive voltage fluctuation on theload side'of the line volt:- age regulator.

Since the limit? switch operating arm 49 andi the neutralizing switch operating camill are se-- cured on the'shaft 34 whichcarries the. switch operating arm 33-, movement of'the arm 33 under the driving influence of the driving means I3 causes similar movement of the arm 43 and;

cam-50; At the outset of the operation'of shifting' the position of the switch I I from the boost position shown'in the diagramltoa neutral position, as described in the preceding paragraph,

the-cam urges the spring biased neutralizing switch blade 14 upwardly'to a position in which the contact82 carried by the blade of the switch "establishes contact with the fixed-contact 19-- of the neutralizing switch to close the circuitthrough thecshading polewinding 42 of theme-'- tor'33 and insert thereinzthe resistor 83, the valueof the resistor 83 being such that itproduoes a torque equaLto "one-half of the-rated torque of the armature 43'" which tends to ro tate the armature'43 in a clockwisedirection; however, with thecontacts- 58 and of the voltmeter 5| closed theshadedpole winding of themotor39- causes'a-full rated torque'onthe armature 43-' which overcomes the established: one-half rated torque set up in the shading-pole winding 42with the result that the armature 43 turns in aoounter-cloekwise direction toeffect the desired'direction of movement of the-switch operating arm-33; This counter-clockwise-move-- mentof theshaft 34 andits associated-parts continuesuntil such timeas the limit switch operating'arm 49' engages" the blade of v the limit switch" causing it to-make-contact witl'rthe' fixed contact 15-01 the limit switch Ii-causing the shading pole-winding ofthemotor 39c to'be grounded: and-ineffective to produce further torque" upon the armature 43- andthus terminate-t the counter-clockwise movement of theshaft 34- While the shading :pole

and its associated 'parts: winding 4l of the motor 39is thus grounded out, it will be noted that theshadingpole winding "of the motor'is still'in'the control circuit.

as the cam' 50 retains the contacts 19 and 82 of the-neutralizing switch 14 closed. This re sults "in'the automatic return'of the switch operating arm to its-rest, or vertical, position under" the clockwise torque imposed upon the armature 43 by the induced current flowing through the shading pole winding '42 of the motor.

9 the cam which permits the spring biased blade of the neutralizing switch 14 to move downwardly to break the circuit made between the contacts 19 and 82.

Let us assume now that the switch I is in neutral position and that the voltage in the line on the load side of the regulator has dropped below the low limit established by the positioning of the low limit contact 59 of the contact making voltmeter 5|. This persisting condition of lowered voltage on the load line side of the regulator in duces a corresponding change in the current in duced in the control winding 23 of the coil l? which in turn is transmitted to the voltmeter 5| causing the indicator and contact needle 56 to be deflected to the left, with reference to the schematic diagram, to a position in which the contact 53 on the needle 55 engages the high limit contact 69 of the voltmeter 5| thus closing the portion of the control circuit which energizes the shading pole winding 42 of the motor 39 to induce a clockwise rotation of the armature 43 of the motor and cause the switch operating arm 33, the limit switch operating arm 49 and the neutralizing switch operating cam 59 to move in a clockwise direction from their inactive or rest positions. The clockwise movement of the switch operating arm 33 carries the tension spring 32 to an over-center position in which it effects the snap action of the switch arm 22 from its neutral contact position to its boost position, wherein the series or booster winding l9 of the coil I1 is connected in series between the power line 6i and the load line 63 to cause the winding l9 to effect a boost action upon the voltage of the load line 83. In conformity with the manner previously described, the initial clockwise movement of the neutralizing switch cam 5% causes the closing of the contacts 13 and 82 of the neutralizing switch 14 to energize the shading pole winding 3| and place the resistance 83 in the circuit thus closed to produce a torque equal to one-half of the rated torque of the armature 43 which tends to rotate the armature in a counter-clockwise direction; however, with the contacts 58 and 59 of the voltmeter 5| closed the shading pole winding 42 of the motor 39 causes a full rated torque on the armature which overcomes the half rated torque set up by the shading pole winding 4| with the result that the armature turns in a clockwise direction to effect the desired movement of the switch operating arm 33. This clockwise motion of the shaft 34 and its associated parts continues until such time that the limit switch operating arm 49 engages and closes the normally open contacts of the limit switch 8|, which action results in the shorting out of the shading pole winding 42 to stop further travel of the switch operating arm 33 in a clockwise direction. This condition persists so long as the voltmeter contacts 58 and 59 remain closed. When the voltage on the load side of the regulator has risen a sufficient amount, the contacts 58 and 59 are separated under the action of movement of the needle 56 of the voltmeter 5|. The breaking of this circuit, by separating the contacts 58 and 59, permits the energized shading pole winding 4| to become effective to return the switch operating arm 33 to its rest position under the influence oi the countar-clockwise rotation of the armature 43 in response to the induced current in the shading pole winding 4| which action is terminated by the breaking of the circuit in the shading pole winding 4| through the lifting action of the cam 50 10 on the blade of the neutralizing switch 14 to separate the contacts 73 and 82.

All of the foregoing description of the automatic operation of the line voltage regulator has been predicated on two premises; the first being that the duration of the excessive voltage fluctuation on the line side of the regulator has persisted in one and the same direction for a period of time great enough to effect the overdamped movement of the indicating and contact making needle 55 through the distance of travel necessary for it to establish contact of its contact 58 with one or the other of the adjustably positioned contacts 59 and 60 of the contact making voltmeter 5|; and the other premise is that the established demand of the load line voltage must continue to persist in the established direction for the period of time delay built into the time delay mechanism M in order to effect the completion of an operating cycle to shift the position of the switch H from its previously established position to its other position to satisfy the demands of the contact making voltmeter or control device I5.

In the absence of the first mentioned time requirement, that being the one suiiicient to establish the control contact within the voltmeter 5|, there will be no effect upon the operating mechanism of the regulator. In the event that the elapsed time of the voltage change requirement after the establishment of the control contact within the voltmeter 5| has been made is less than the time delay period of the time delay mechanism i i, the breaking of the established contacts of the voltmeter 5| will cause the mechanism to return to its rest position without effecting a shift of position of the switch E In the event that the voltage requirement of the load line circuit is not satisfied when the regulator is in boost position and the voltage requirement continues to persist, the device will remain in boost position without detrimental effect upon the operating mechanism due to the presence and function of the limit switch in the control circuit which becomes effective to stop the movement of the switch operating arm 33 when the limit switch closes.

In some instances where this condition of unsatisfied voltage requirements persist, when the regulator is retained in boost position appears with undesired frequency, it is possible to install a second voltage regulator in the line, in cascade relationship with the first regulator, to alleviate this condition.

From the foregoing description of the illustrative embodiment of the present invention, it will be apparent that a new and improved line voltage regulator has been provided which functions automatically to maintain the voltage on the load line side of the regulator within the predetermined and permissible limits as set by the adjusted positioning of contacts on a voltage responsive control device.

It should be noted that the line voltage regulator of the present invention provides a new and improved device which is of low cost design, compact construction and assembled in a manner which makes it readily accessible for inspection, adjustment, repair or even replacement if necesary of unitary portions of the regulator. The entire assembly is relatively light in weight and adapted for pole mounting with special provision being made for positioning the control device either on the exterior wall of the enclosure tank or remote therefrom as at the base of the mountsiderable detail in the foregoing specification, it

is to be understood that various changes may be made in its embodiment without departing from or sacrificing any of the advantages hereinafter claimed.

I claim:

1. A step type line voltage regulator comprising a unitary core and coil structure, said coil including shunt and series windings in fixed autotransformer relationship, and a control winding, said coil windings providing a constant ratio of transformation between the load side voltage and said control winding, 9. power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil contacts, a multiple position switch operating member having a neutral position and a pair of switch operating positions, driving means for said switch operating member including time delay means, a voltage sensitive control device responsive to excessive voltage fluctuation on the load line to energize said driving means to move said switch operating member only upon the persistence of the excessive voltage fluctuation for a period of time not less than that required for the operation of said time delay means in one direction from its neutral position upon an excessive drop in control voltage and in the opposite direction upon an excessive rise in control voltage, and an auxiliary driving means operative to return said switch operating member to its neutral position upon completion of any change of position of said switch.

2. A step type line voltage regulator comprising a unitary core and coil structure, said coil including shunt, series and control windings in fixed autotransformer relationship and providing a constant ratio of transformation between the load line voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having neutral and operating positions, driving means for said switch operating member including time delay means, and a voltage sensitive control device responsive to v oltagefluctua tion beyond predetermined limits in said control winding to energize said driving means to shift the position of said switch through'the medium of said operating member upon the persistence of said excessive voltage fluctuation to maintainthe load line voltage within the predetermined limits of fluctuation, said time delay means insuring the necessity of a persisting demand of said control device for a period of time not less than that required for the operation of said time delay means prior to the changing of said switch position.

3. The combination with a step type line voltage regulator including a, unitary core and coil structure, said coil having shunt, series and control windings in fixed autotransformer relationship and providing a constant ratio of transformation between the load line voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having neutral and switch operating positions, "driving means for moving said switch operating member, and

time delay means in said driving means, of'a control circuit for said regulator, said control circuit including a contact making voltmeter energized from current induced in said control winding, said contact making voltmeter being responsive to excessive fluctuation of voltage in the load line to energize said driving means to shift the position of said switch only upon the persistence of the excessive voltage fluctuation for a period of time not less than that required for the operation of said time delay means to selectively insert said series winding of said coil in the circuit between the power and load lines to increase the load line voltage in response to an excessive drop in the load line voltage or to remove the series winding from its boosting connection in response to an excessive rise in load line voltage.

4. The combination with a step type line voltage regulator including a unitary core and coil structure, said coil having shunt, series and control windings in fixed autotransformer relationship and providing a constant ratio of transformation between the load line voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having neutral and switch operating positions, driving means for moving said switch operating member, and time delay means in said driving means of a control circuit for said regulator, said control circuit ineluding a contact making voltmeter energized from current induced in said control winding, said contact making voltmeter being responsive to excessive fluctuation of voltage in the load line to establish a control contact and energize said driving means to shift to position of said switch through the medium of said operating member only upon the persistence of the excessive voltage fluctuation for a period of timenot less than that required for the operation of saidtime delay means to maintainthe load line voltage within predetermined limits of fluctuation by selectively inserting or cutting out said series winding of said coil in the circuit between the power and load lines to increase the load line voltage in response to an excessive drop or decrease the load line voltage in response to an excessiverise, whereby the load line voltage is maintained automatically within predetermined and permissible limits of fluctuation.

5. The combination with a step type line voltage regulator including a unitary cor and coil structure, said coil having shunt, series and control windings in fixed autotransformer relationship and providing a constant ratio of transformationbetween the load line voltage and said control winding, 2. power line contact, aplurality of coil tapcontacts, a switch movableto selectively connect said power line and coil-tap contacts, a switch operating member having neutral and operating positions, and a shaded pole motor for driving said switchoperating member, of a control circuit for the regulator, said control circuit including a voltage sensitive control device energized from current induced in said control winding or said coil, saidvoltage sensitive device being responsive to excessive fluctuation in the load line to establish a control contact and encrgize said shaded pole motorto changetheposition of said switch through the medium of said switch operating member to selectively insertsaid series winding ofsaid coil in the "circuitb'etween the power line and'said loadline "to increase the load line voltage in response to anexoessive drop in control winding voltage or to cut out said series winding from between the power and load lines to decrease the load line voltage in response to an excessive ris in said control winding voltage, whereby the load line voltage is maintained automatically within predetermined and permissible limits of fluctuation.

6. The combination with a step type line voltage regulator including a unitary core and coil structure, said coil having shunt, series and control windings in fixed autotransiormer relationship and providing a constant ratio of trans formation between the load line voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having a neutral and switch operating position, driving means for moving said switch operating member from neutral to an operating position, and driving means for returning said switch operating member to neutral position upon completion of a change of position of said switch, of a control circuit for said regulator, said control circuit including a contact making voltmeter energized from current induced in said control winding, said contact making voltmeter being responsive to excessive fluctuations of voltage in the load line to establish a control contact and energize said driving means to move said switch operating member in one direction from its neutral position upon an excessive drop in load line voltage to shift the position of said switch and thereby insert said series winding of said coil into the circuit between the power and load lines to increase the load line voltage and move said switch operating member in the opposite direction from its neutral position upon an excessive rise in load line voltage to shift the position of said switch and thereby remove said series winding from the circuit between the power line and load line to decrease the load line voltage, and control means responsive at the completion of a shift of position of said switch to energize said driving means for returning said switch operating member to its neutral position.

'7. The combination with a step type line voltage regulator including a, unitary core and coil structure, said coil having shunt, series and control windings in fixed autotransiormer relationship and providing a constant ratio of transformation between the load line voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having neutral and switch operating positions, a shaded pole motor for driving said switch operating member from neutral to an operating position, and a pole shading winding for returning said switch operating member to neutral position upon completion of a change of position of said switch, of a. control circuit for the regulator, said control circuit including a contact making voltmeter energized from current induced in said control windings of said coil, said contact making voltmeter being responsive to excessive fluctuation of voltage in the load line to establish a control contact to energize said shaded pole motor to shift the position of said switch through the medium of said switch operating member to maintain th load line voltage within predeter mined limits of fluctuation by selectively inserting or cutting out said series winding of said coil in the circuit between the power line and load line to increase the load line voltage in response to an excessive drop or decrease the load line voltage in response to an excessive rise, and control means responsive at the completion of a shift of position of said switch to energize said pole shading winding for returning said switch operating member to its neutral position.

8. The combination with a step type lin voltage regulator comprising a core and coil structure, a, power line contact, a plurality of coil tap contacts, a switch movable to selectively connect said power line and coil tap contacts, a switch operating member having neutral and operating positions, driving means for said switch operating member including time delay means, and a potential transformer, of a control circuit for the regulator, said control circuit being energized by said potential transformer and including a voltage sensitive control device operative in response to excessive voltage fluctuation in the load line to energize said driving means to shift the position of said switch through the medium of said switch operating member, said time delay means in said driving means serving to insure the shifting of said switch only upon the presistent excessive voltage fluctuation for a period of time equal to that of the time delay means.

9. In a step type line voltage regulator the combination of a unitary core and coil structure, said coil having shunt and series windings in fixed autotransformer relationship, and a control winding, said coil windings providing a constant ratio of transformation between the load line Voltage and said control winding, a power line contact, a plurality of coil tap contacts, a switch movable to selective connect said power line and said coil tap contacts, operating means for said switch, including driving means incorporating a time delay means, and control means responsive to persisting excessive voltage fluctuation in the load line to energize said switch operating means to shift the position of said switch only upon the persistence of the excessive voltage fluctuation for a period of tim not less than that required for the operation of said time delay means to selectively place said series winding of said coil into the circuit between the power and load lines in response to an excessive drop in load line voltage or to remove-said series winding from the last mentioned circuit in response to an excessive rise in load line voltage to thereby automatically maintain the load line voltage within predetermined limits of fluctuation.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 921,299 Sprong t al May 11, 1909 1,903,999 Holden et a1 Apr. 18, 1933 2,009,383 Blume July 30, 1935 2,283,741 Lennox May 19, 1942 2,380,784 Patin July 31, 1945 2,449,367 Boyajian Sept. 14, 1948 2,563,179 Malsbary Aug. 7, 1951 

